1. Field of the Invention
The present invention is generally related to medical devices, systems, and methods which apply (or otherwise make use of) energy, as well as to other fields in which accurate control over electrical energy is beneficial. In exemplary embodiments, the invention provides an energy generating and control apparatus for the selective delivery of energy dosage during catheter-based treatment for luminal diseases, particularly for atherosclerotic plaque, vulnerable or “hot” plaque, and the like.
2. Discussion of Related Art
Physicians use catheters to gain access to, and repair, interior tissues of the body, particularly within the lumens of the body such as blood vessels. For example, balloon angioplasty and other catheters often are used to open arteries that have been narrowed due to atherosclerotic disease.
Balloon angioplasty is often effective at opening an occluded blood vessel, but the trauma associated with balloon dilation can impose significant injury, so that the benefits of balloon dilation may be limited in time. Stents are commonly used to extend the beneficial opening of the blood vessel.
Stenting, in conjunction with balloon dilation, is often the preferred treatment for atherosclerosis. In stenting, a collapsed metal framework is mounted on a balloon catheter that is introduced into the body. The stent is manipulated into the site of occlusion and expanded in place by the dilation of the underlying balloon. Stenting has gained widespread acceptance, and produces generally acceptable results in many cases. Along with treatment of blood vessels, particularly the coronary arteries, stents can also be used in treating many other tubular obstructions within the body, such as for treatment of reproductive, gastrointestinal, and pulmonary obstructions.
Restenosis or a subsequent narrowing of the body lumen after stenting has occurred in a significant number of cases. More recently, drug coated stents (such as Johnson and Johnson's Cypher™ stent, the associated drug comprising Sirolimus™) have demonstrated a markedly reduced restenosis rate, and others are developing and commercializing alternative drug eluting stents. In addition, work has also been initiated with systemic drug delivery (intravenous or oral) that may also improve the procedural angioplasty success rates.
While drug-eluting stents appear to offer significant promise for treatment of atherosclerosis in many patients, there remain many cases where stents either cannot be used or present significant disadvantages. Generally, stenting leaves an implant in the body. Such implants can present risks, including mechanical fatigue, corrosion, and the like, particularly when removal of the implant is difficult and involves invasive surgery. Stenting may have additional disadvantages for treating diffuse artery disease, for treating bifurcations, for treating areas of the body susceptible to crush, and for treating arteries subject to torsion, elongation, and shortening.
A variety of modified restenosis treatments or restenosis-inhibiting occlusion treatment modalities have also been proposed, including intravascular radiation, cryogenic treatments, ultrasound energy, and the like, often in combination with balloon angioplasty and/or stenting. While these and different approaches show varying degrees of promise for decreasing the subsequent degradation in blood flow following angioplasty and stenting, the trauma initially imposed on the tissues by angioplasty remains problematic.
More recently, still further disadvantages of dilation have come to light. These include the existence of vulnerable plaque, which can rupture and release materials that may cause myocardial infarction or heart attack.
A number of alternatives to stenting and balloon angioplasty so as to open stenosed arteries have also been proposed. For example, a wide variety of atherectomy devices and techniques have been disclosed and attempted. Despite the disadvantages and limitations of angioplasty and stenting, atherectomy has not gained the widespread use and success rates of dilation-based approaches.
Additionally, methods in the art of debulking diseased tissue to reduce or eliminate lesions, such as atherectomy and ablation, generally provide few if any means for protecting healthy tissue from being damaged through the course of treating diseased tissue.
In light of the above, it would be advantageous to provide new devices, systems, and methods for remodeling of the lumens of the body, and particularly tissue of the blood vessels. It would further be desirable to avoid significant cost or complexity while providing structures which could remodel body lumens without having to resort to the trauma of extreme dilation, damage to neighboring healthy tissue, and to allow the opening of blood vessels and other body lumens which are not suitable for stenting.